In the past, I've owned both. The MES died about a year ago and the Bradley (even though several years old) was good enough that someone relieved me of it about 4 years ago on a weekend I was out of town.
Generally speaking Bradley was a little more expensive, but the old one I had was pretty durable. It worked well, and was a quality unit.
The good news is that Bradley has announced in January 2015 they will be building a manufacturing facility in Phoenix AZ., so they will be American Made!
I actually always worried about the MES due to the wiring issues, and mine had an over temperature problem and it started a fire that damaged the door seal. Masterbuilt gave me the run around, so I finally re-cycled it due to the wife's insistence.
If you are on a budget, the MES is fine, and does a great job. I did invest in the A-maze-n-pellet smoker which solved my personal problem regarding a lack of smoke. Additionally, Masterbuilt is normally pretty good about sending parts on units that were found to be lacking in the quality department.
That is a reason IMHO that a lot of people on the forum like them. However, Bradley parts are available if needed.
My real feeling is that I would prefer an American Made unit, as my Stick burner is. So I have to give the edge to Bradley; but really enjoyed my MES smoker and it lasted for 3 - 4 years.
There are some real masters out there using MES.
Both are out there in abundance, and you might just go to a Cab*ela's, Sa*m's Club, or other retailer to get an idea of what might fit your specific need.
In any event, best of luck with whichever you decide to take home.